The ability to reduce the surface tension of water is of great importance in the application of water-based formulations because decreased surface tension translates to enhanced substrate wetting during use. Examples of water-based compositions requiring good wetting include coatings, inks, adhesives, fountain solutions for lithographic printing, cleaning compositions, metalworking fluids, agricultural formulations, electronics cleaning and semiconductor processing compositions, personal care products, and formulations for textile processing and oilfield applications. Surface tension reduction in water-based systems is generally achieved through the addition of surfactants, resulting in enhanced surface coverage, fewer defects, and more uniform distribution. Equilibrium surface tension (EST) is important when the system is at rest, while dynamic surface tension (DST) provides a measure of the ability of a surfactant to reduce surface tension and provide wetting under high speed application conditions.
The importance of the ability of a surfactant to achieve low surface tension at low use levels, the ability to affect foaming performance, and the surfactant's ability to provide efficient emulsification and solubilization are all of considerable industrial importance, as is well-appreciated in the art. And, although equilibrium surface tension reduction efficiency is important for some applications, other applications may require both equilibrium and dynamic surface tension reduction.
The foaming characteristics of a surfactant are also important because they can help define applications for which the surfactant might be suitable. For example, foam can be desirable for applications such as ore flotation and cleaning. On the other hand, in coatings, graphic arts and adhesive applications, foam is undesirable because it can complicate application and lead to defect formation. Thus foaming characteristics are frequently an important performance parameter.
The wide variety of applications for which surfactants are used, and the resultant variation in performance requirements, results in a need for a correspondingly large number of surfactants adapted to these various performance demands, and a need for suitable methods for making them.